Shoe manufacture



Dec. 17, 1968 M. R. RADCLIFFE ETAL. 3,416,244.

SHOE MANUFACTURE Filed Feb.` .18, 1964 [raven LO 11s /V/lzvon R.Radcliffe William Tabr'off United States Patent O 3,416,244 SHOEMANUFACTURE Milton R. Radcliffe, Marblehead, and William Tabrotf,Peabody, Mass., assignors to United Shoe Machinery Corporation,Flemington, NJ., Boston, Mass., a corporation of New Jersey Filed Feb.18, 1964, Ser. No. 345,773 15 Claims. (Cl. 36--30) The present inventionrelates to shoe manufacture and more specifically to shoe bottomfilling.

In Shoemaking, particularly welt and similarly constructed shoes, anupper is pulled over a last and attached by its lasting margin to aninsole previously positioned on the last. This causes a cavity to beformed which is defined as to the bottom by the insole and peripherallyby the inner edge of the lasting margin or by the insole rib. In orderthen to lay on an outsole properly it becomes necessary to fill or levelthis cavity. The usual practice is to do so with what is referred to asa shoe bottom filler, and, then following that the outsole is laid.

Shoe bottom filling may be effected in various ways. In one practice apre-cut insert is used. More common, however, is the use of masticfillers. These are introduced into the cavity in fiuid or workable stateand set up in situ to a solid state. In the solid state, that is in setup or stiffened condition the fillers are preferably flexible andresilient in nature.

In theory at least the practice of using a mastic filler allows theattainment of better or more complete filling or to state it againbetter conformation between the filler and the cavity. It is the mastictype filler with which the present invention is particularly concerned.

Present mastic shoe bottom fillers are most commonly asphalt or otherresin and cork mixtures. To place them in a fiuid or workable state theyare heated or solvated using a common, volatile organic solvent.

Although the mastic fillers presently known contribute advantages to theshoemaking art, they have certain shortcomings. Perhaps the most seriousof these involves shrinkage on setting. This is particularlytroublesome. Aggravating this situation further is the fact that notonly is it difficult to arrive at a bottom filler which completely fillsa shoe bottom cavity on setting, but most shoemakers dictate that thefilling should be carried out to the extent that it contributes a convexconfiguration to the outsole of a finished shoe. This is commonlyreferred to as a crown or crowning. It is in effect over-filling thecavity. Filling to that extent, with present mastic fillers, caninterfere without sole laying and attaching. Other difficulties withmastic fillers that are presently known include their proneness to breakdown, crack, fragment or disintegrate and fioat. The latter citeddifficulties reliect that it is desirable to unitize the various shoebottom parts, to wit: insole, outsole, as well as the shank which iscommonly included, and the filler.

It is an object of this invention to provide a shoe bottom filler whichmay be introduced into a shoe bottom cavity in fiuid form -where it setsconveniently to a solid state, and in the latter state has excellentconformation with the shoe bottom cavity.

It is another object of this invenion to provide a shoe bottom fillerwhich contributes to convenience in obtaining crowning in an outsolelaid on a shoe in which the filler is included.

It is another object of this invention to provide a shoe bottom fillerwhich on setting serves to unitize the various shoe bottom components,to wit: insole, outsole and shank, together with the filler.

It is another object to :provide an improved method for filling a shoebottom cavity.

3,416,244 Patented Dec. 17, 1968 ice These and other objects areobtained in a shoe bottom filler which is initially in fiuid state beingbased on a moisture-curable isocyanate-containing prepolymer. In fiuidstate the subject filler may be introduced into a shoe bottom cavitywhere with exposure to moisture it sets up to a solid state conformingwith or filling or leveling the cavity to a predetermined extent.

In order to illustrate the present invention the following drawings areincluded in which:

FIG. l is a bottom plan view of a lasted, shoe upper assembly shownprior to filling the shoe bottom cavity;

FIG. 2 is a bottom plan view of a shoe upper assembly shown after theshoe bottom cavity has been filled;

FIG. 3 is a section along the line III- III of FIG. 2; and

FIG. 4 is a transverse sectional view of a finished shoe assembly ofGoodyear welt construction.

An embodiment of the present invention will now be described withreference to the drawings in which a shoe upper 10 is shown pulled overa last 12, see FIG. 3. Initially insole 14 is positioned on the last 12by means of tacks 16. Insole 14 includes a rib 18. A shank piece 20 isprelimnarily stationed on the insole 14 by staples 21 which pass throughholes 22 located toward the ends of the shank piece 20. Referring toFIG. 1, the lasting margin 10a is attached to an insole 14 in aconvenient manner as by adhesive attachment or the like. The lastingedge 10b which is the inward edge of the lasting margin 10a may alsoextend upwardly of the same and is shown trimmed to approximately thesame height as that of the rib 18. A shoe bottom cavity 23 is formed,being defined as to its bottom by the insole 14 and peripherally by therib 18. In the case of a fiat-lasted shoe, the cavity 23 would bedefined peripherally by the edge 10b of the lasting margin 10a.

A welt 24 is included in the assembly. This is attached by stitching 25to the rib 18, see specifically FIGS. 3 and 4.

Continuing with reference to FIG. 2, the cavtiy 23 is caused to be atleast partially filled by a predetermined amount of the mastic ller 26of this invention. As shown, mastic filler 26 is introduced into thecavity 23 in fluid form from a nozzle 28 of a mastic dispensingapplicator, not shown, which maintains the mastic filler in essentiallymoisture-free condition prior to dispensing or extruding the same.Following that, the mastic filler 26 may be distributed throughout thecavity 23 by a spreading tool 30, or, as otherwise desired. While themastic filler 26 may be distributed throughout the entire area of cavity23 it is generally restricted to the forward end and partially in theshank area of cavity 23 as indicated in FIG. 2. This is sufficient tofacilitate outsole laying and obtain the desired unification of variouscomponents.

The mastic filler 26 is of foamable or expandable nature. Thischaracteristic serves to cut down Weight. In addition however, themastic filler 26, when it assumes a foamed or expanded solid state isliexible and resilient, and if desired, may be compressible in order forit to provide a cushioning effect when it is in a final solidified form.

Turning to FIG. 4, after the mastic Afiller 26 is introduced into thecavity 23 an outsole 32 may be laid on and permanently attached vbystitching 34. Other shoemaking loperations in the nature of finishingusually practiced may be carried out as desired.

As previously indicated, the mastic filler 26- sets up or is cured insitu to a solid state within the cavity 23. In solid state the masticfiller 26 has a cellular or expanded structure and exhibits a fiexible,resilient nature.

A crown effect may be obtained in the outsole 32 by tak-` ing advantageof the fact that the mastic filler 26 expands with curing.

Following the introduction of mastic iiller 26 into the cavity 23v it isnot necessary to allow hiatus in time before laying on outsole32.Rather, the preferred practice is to carry out the outsole layingoperation as soon as possible following tilling the cavity 23 withmastic iller 26.

As can be noted from FIG. 4, on setting, the iiller 26 not only servesto lill the cavity 23 but also serves to unitize the various shoe parts,to wit, the outsole 32, shank 20, insole 14, etc. into a consolidated,yet flexible whole.

The mastic filler which can be used in practice of the present inventionis an isocyanate-containing polymer. In its initial, Huid or workablestate it is a prepolymer which is moisture-curable. Moisture-curableindicates that the prepolymer, and more specifically the free isocyanategroups contained in the same, have the capacity to react with water,either in vapor or liquid state to effect curing to an expanded,flexible and resilient solid state. The moisture required for reactionmay be provided by the atmosphere, that is it may be ambient in nature,or it may be added from a separate source. The capacity to bemoisture-cured by means of ambient moisture represents a convenience andso is desirable from a Shoemaking consideration.

Prepolymers which may be used are those based on polyols. These includelin addition to polyhydric alcohols, the polyester polyols and polyetherpolyols. Principally, the polyesters and polyether polyols are used.Examples of the polyester polyols are those based on adipic acid, dimeracid, phthalic acids, phthalic acid anhydrides, castor oil, etc. whilethe polyethers are exemplied by those based on glycerine, trimethylolpropane, sorbitol and pentaerythritol to which polypropylene oxide maybe added to increase the molecular weight. Examples of the polyhydricalcohols which may be used include those which are chain extended suchas the polyhydric polypropylene oxide, polyethylene oxide, etc. In orderthat the prepolymers obtained have desirable exibility or crackabilityit is recommended that the polyol used have a molecular weight in therange 500 to 2500 per hydroxyl group present on the polyol.

In producing the prepolymers, the polyols are reacted with an excess ofisocyanate to provide moisture-curable isocyanate-containing prepolymershaving an excess of free yor unreacted isocyanate groups. The excessisocyanate groups'then contained in the prepolymer are then capable ofreacting with moisture causing the prepolymer to cure to an expanded,ilexible, resilient solid state. In order that the expanding-curingreaction be effectively orestalled until filling itself is carried outit is prescribed that the polyols for reaction with the polyisocyanatebe in at least essentially moisture-free condition and that also thepolyisocyanate-polyol reaction be carried out under at least essentiallymoisture-free conditions.

The polyols, for use in the prepolymer may be a diol, triol, and otherpolyhydrics in addition to blends of the same. When reacted with apolyisocyanate a prepolymer may be provided having an excess ofisocyanate groups. The excess is free isocyanate groups desired on theprepolymer is preferably greater than two free isocyanate groups on amol ratio basis in order that a resilient, flexible, solid ller beobtained as a result of moisturecuring. With less than the indicatedamount of free isocyanate groups present in the prepolymer theprepolyrner does cure ybut in doing so does not provide a solid fillerwhich is iiexible, resilient and coalesced into a unitary -form of thenature of rubber, such as is preferred in practice of this invention. Inthe event that the polyol is a diol, a triisocyanate such aspolymethylene polyphenyl isocyanate (PA-PI) may be used to obtain aprepolyrner having this desired excess of isocyanate groups. If thepolyol is .a triol, a diisocyanate such as toluene diisocyanate (TDI),etc. may be used to obtain this result.

The isocyanate containing prepolymers are expandable withmoisture-curing. The moisture, that is the water, when made availablereacts with the isocyanate groups to provide carbon dioxide which causesfoaming or expansion together with curing. Auxiliary blowing agents maybe added if desired, but are no-t necessary. These would include thevarious uorocarbons generally used for this purpose. In addition variouscatalysts, stabilizers such as moisture yscavengers and the like may beincluded.

The prepolymers for .use in this invention may include extenders such asthe petroleum derived, high aromatic content hydrocarbon oils, of thetype used as rubber extenders (examples are the Dutrexes which is atrademark designation of the Shell Oil Company), also various naturaloil derived extenders such as tall oil, cottonseed oil, corn oil and thelike may also be used for a similar purpose. Fillers such as pitch,bitumins, ashphalts, synthetic polymers such as polyvinyl chloride,polyestrene, etc. may also be used to extend the prepolymers. Otherllers which may be included are ground cork, clay, sulfur, glass bers,wood pulp, foam glass, gypsum,l also alumina silicates, aluminahydroxides, etc. It is proposed that with respect to extenders andfillers as well as other additives to the prepolymer that they be freeof moisture and non-reactant in nature with the free isocyanate groupscontained on the prepolymer. The various lillers and extenders may beincluded in the prepolymer, on a weight ratio of 1:4 to 4:1 with goodresults.

The following examples are included for the purpose of furtherillustrating the invention.

EXAMPLE I Prepolymer Preparation A-Formulaton Part l: Ppw. PolypropyleneGlycol (3000 mol wt.) 600 Dutrex 739 (aromatic petroleum fraction) 1200Sulfur 3600 Part 2:

PAPI (polymethylene polyphenyl isocyanate) 160 N,N tetramethyl butanediamine 1.6

Part l is dehydrated under vacuum of 30 mm. Hg and C. for a period oftwo hours in a Baker-Perkins dough mixer. The ingredients of Part 2 arethen added to the mixer and while maintaining the vacuum, reaction isallowed to proceed for a period of two hours. The reaction product isobtained as a heavy, pasty yet spreadable or workable mixture. It isremoved from the mixer and packed into a tive gallon metal containerunder vacuum conditions. The reaction product is noted to have a doughyconsistency.

Prepolymer Preparation ,fl-Formulation Part l: Ppw. Polypropylene glycol(3000 mol wt.) 600 Dutrex 795 (aromatic petroleum fraction) 1200Molecular Sieve S-A powder (synthetic crystalline alumina-silicate) 20PAPI Part 2:

Sulfur (Rubber Makers) 3600 Ground cork 340 The individual ingredientsof both Parts l and 2, exclusive of the polyisocyanate, are dehydratedunder 30 mm. Hg vacuum and 80 C. in a Baker-Perkins dough mixer. Part 1ingredients are then tumbled for two hours in the mixer, again under 30mm. Hg and 80 C. Thereafter, one half of the sulfur is added and afterfive minutes of tumbling the remainder of the sulfur is added. Againafteriive minutes tumbling time the cork is added and tumbling continuedfor another tive minute period. The product of the mixer is fluid innature and is discharged and directed into a ve gallon containerquickly. The container is rapidly closed With minimum air space.

Prepolymler Preparation C-Formulation Part 1: Ppw. Propylene oxiderunout of hexane triol (3300 mol wt.) 240 Toluene diisocyanate 40 Talloil 1640 Part 2 Sulfur 1000 Exclusive of the toluene diisocyanate, theingredients of both Parts l and 2 are dehydrated under 30 mm. Hg vacuumat 80 C. for a period of two hours. The ingredients of Part 1 are thencharged separately into the mixer and tumbled for two hours under theconditions specified above for dehydrating. Thereafter, half the sulfurof Part 2 is added and tumbling continued for 10 minutes. The remainderof the sulfur of Part 2 is added and tumbling continued for another 30minutes. The prepolymer is removed from the mixer and transferred to ave gallon container which is then tightly closed with a minimum of airspace retained in the same.

Shoe cavity filling D Immediately prior to utilization each of theprepolymer fillers prepared according to paragraphs A-C above, arecharged into a Graco Powero Extrusion Unit (Model 225-95/designed foruse with a five gallon drum). This involves removing the covers from thecontainers storing the 'prepolymer iillers and introducing into each theintake of the Extrusion unit. The intake is fitted with a horizontallyflaring O-ring gasket which fits tightly at its periphery with theinterior sides of the storing container (v'e gallon).

The Extrusion unit is used to provide each of the shoe bottom cavitiesof a number of mens shoes, size 81/2, leather upper assemblies whichinclude metal shantk pieces and are supported on lasts, with 30 gramcharges of the prepolymer llers. The filler charge is actually depositedin the form of a ribbon approximately one inch wide and a quarter inchthick at the forward or toe end of the cavity and distributed back partway through the shank area. Distribution is facilitated by means of aspatula.

After filling, leather outsoles are immediately laid on the upperassemblies by cement spotting, and following that, the assemblies areplaced in a soling press and outsole stitching is then carried out. Theshoes are then finished in the usual fashion and the lasts removed. Atthis time it may be noted that the outsoles are crowned or to state itdicerently have a distinct convex shape.

4Shoes produced as above are then wear-tested for an extended period.Wet and dry iexing tests are also carried out on them. The shoes arethen slit through to show their structures in cross-section. At thispoint it is noted that in each of the shoes the ller has a foamed orcelled structure. The filler is resilient and flexible; and does notshow cracking, fragmentation or disintegration of any type. In additioneach of the shoes shows good unitization or bonding between theoutsoles, Shanks, and insoles through the fillers. y

It will thus be seen that the objects set forth above among those madeapparent from the preceding description, are eiiiciently obtained and,since certain changes may be made in carrying out the above method andin the shoe assembly set forth Without departing from the scope of theinvention, it is intended that all matter contained in the abovedescription and shown in the accompanying drawings shall be interpretedas illustrative and not in a limiting sense.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent of the United States is:

1. A method for bottom filling a shoe which comprises (a) at leastpartially filling a bottom cavity of a shoe assembly with a masticiiller which comprises moisturecurable isocyanate-containing prepolymerin fluid form, (b) laying an outsole on the shoe assembly and (c)allowing the prepolymer to set to a solid state by exposure to moisture.

2. A method according to claim 1 wherein the prepolymer contains greaterthan two free isocyanate groups in mol ratio.

3. A method according to claim 1 wherein the prepolymer comprises atriisocyanate and a diol.

4. A method according to claim 1 wherein the prepolymer comprises adiisocyanate and a triol.

5. A method according to claim 1 wherein the isocyanate-containingprepolymer is extended with a hydrocarbon oil having a high aromaticcontent.

6. A method according to claim 1 wherein the prepolymer is combined witha solid iiller while in uid form.

7. A method according to claim 6 wherein the solid ller is sulfur.

8. A method according to claim 6 wherein the solid ller is ground cork.

9. A shoe assembly having a bottom. cavity lled with a mastic filler inexpanded solid state comprising polyurethane obtained by in situ curinga `quantity of a moisture-curable isocyanate-containing prepolymerlocated within said bottom cavity and having an outsole laid on the sameprior to said curing in situ.

10. A shoe assembly according to claim 9 wherein the prepolymercomprises a triisocyanate and a diol.

11. A shoe assembly according to claim 9 wherein theprepolymer-comprises a diisocyanate and a triol.

12. A shoe assembly according to claim 9 wherein the prepolymer isextended by a hydrocarbon oil having a high aromatic content.

13. A shoe assembly according to claim 9 wherein the mastic llerincludes a solid filler.

14. A shoeassembly according to claim 13 wherein the solid filler issulfur.

15. A shoe assembly according to claim 13 wherein the solid ller isground cork.

References Cited UNITED STATES PATENTS 1,909,089 5/1933 Beckwith 12-'148X 2,096,511 10/1937 Gordon 12-148 X 2,905,582 9/1959 Coleman et al.154-139 3,061,475 10/1962 Wallace 117-155 3,116,501 1/1964 Markevitch36-14 X OTHER REFERENCES Dombrow, B. A.; Polyurethanes, RheinholdPublishing Corp., N.Y., 1957, pp. 24 and 25.

PATRICK D. LAWSON, Primary Examiner. H. H. HUNTER, Assistant Examiner.

U.S. C1. X.R.

9. A SHOE ASSEMBLY HAVING A BOTTOM CAVITY FILLED WITH A MASTIC FILLER INEXPANDED SOLID STATE COMPRISING POLYURETHANE OBTAINED BY IN SITU CURINGA QUANTITY OF A MOISTURE-CURABLE ISOCYANATE-CONTAINING PREPOLYMERLOCATED WITHIN SAID BOTTOM CAVITY AND HAVING AN OUTSOLE LAID ON THE SAMEPRIOR TO SAID CURING IN SITU.